LIBRO-CONGRESO-CITRUS

samples, while the other 11 showed increased expression in the on-crop samples against off-crop samples.
These spots were identified by MALDI-MS or LC-MS-MS. The only protein with increased expression in the offcrop
samples was putative monocopper oxidase precursor, while the up-expressed proteins in on-crop leaves
were catalase, monodehydroascorbate reductase, Fe-superoxide dismutase, glutathione peroxidase, and
three proteins related to response stress. Thus according to these results, generally, in the off-crop samples,
proteins with oxidoreductase activity are down-regulated, while in the on-crop samples the proteins related
to stress response and to oxidoreductase activity are up-regulated. Therefore, the redox state is different for
off-crop and for on-crop Citrus leaves.
This work has been supported by the Project INIA RTA2009-00147-C02 and Fundación AgroAlimed.
S03P11
Genomic compositions and origins of Citrus sinensis, Citrus clementina and Citrus poonensis as
revealed by genome-wide analysis of citrus ESTs
Zhong G.Y. 1 , Wu B. 2 , Zeng J.W. 1 , Jiang B. 1 , and Yang R.T. 2
1 Institute of Fruit Tree Research, Guangdong Academy of Agricultural Science, China; and 2 Citrus Research Institute, Southwest University,
China. zhongyun99cn@163.com
The origins of Citrus sinensis, Citrus clementina and Citrus poonensis are largely unknown. A genome-wide
analysis of citrus EST sequences was performed in this study to address this issue. A considerably high level
of SNP polymorphisms in citrus was found by analyzing ESTs. The interference from the allelic expression
bias associated with EST analysis was eliminated by using only the unigenes with enough sequence coverage.
Two approaches, haplotype comparison and phylogenetic analysis were used to analyze the 359 different
gene loci of citrus. It was shown that all the three species, C. sinensis, C. clementina and C. poonensis are
genome-wide heterozygous. Inference from analyzing EST data was that C. clementina was derived from
a cross between a mandarin and C. sinensis, and the mandarin was confirmed to be Citrus deliciosa by
genotyping 25 representative SNPs. Statistically C. sinensis must be originated from three consecutive
crosses, i.e., [(pummelo × mandarin) × pummelo or pummelo × (pummelo × mandarin)] × mandarin, and
the supposed immediate mandarin parent was experimentally searched but not found. The evolution and
domestication of citrus and the significance of high level of SNP polymorphisms were discussed. Information
from ESTs provided some clues to the elucidation of the heterosis mechanism leading to the superiority of
the three most important and widely cultivated citrus. EST based analysis and SNP genotyping are valuable in
inferring the origins of cultivated Citrus species. The origins of C. sinensis, and C. clementina were revealed.
The genome of C. poonensis was analyzed.
S03P12
Genomic sequencing and comparative analysis of Citrus platymamma (Byungkyool) by using
next-generation sequencing technology
Chung S.J. 1 , Han S.I. 2 , Jin S.B. 3 , Kim Y.W. 1 , Yun S.H. 4 , Riu K.Z. 2 , and Kim J.H. 2
1 Research Institute for Subtropical Horticulture, Jeju National University, Korea; 2 Faculty of Biotechnology, College of Applied Life
Science, Jeju National University, Korea; 3 Subtropical & Tropical Organism Gene Bank, Jeju National University, Korea; and 4 Citrus
Research Station, National Institute of Horticultural & Herbal Science, Rural Development Administration, Korea. kimjh@jejunu.ac.kr
Next-generation sequencing (NGS) technologies are being utilized for de novo sequencing, genome resequencing,
and whole genome and transcriptome analysis. Citrus platymamma (Byungkyool) has been known
to be a native citrus species in Jeju Island, South Korea. In this study, we have sequenced C. platymamma
genome to analyze genome structure and gene function. Genomic DNA was obtained from leaves of C.
platymamma and about 25 Gb short-read sequences produced by the Illumina paired-end sequencing
technology. The initial assembly was contained 321 Mbp of C. platymamma genome in 20,818 scaffolds with
N50 size of 60Kbp. These scaffolds contained 176,765 contigs in which N50 size was 3.5 Kbp. Comparison
with the sweet orange sequence, a total of 40,905 genes of C. platymamma were confirmed. This genome
sequence data will be used to characterize potential roles of new genes in Byungkyool and can be used in
comparative studies of other Citrus species.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 69
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